Ladder



E. w. CARLSON LADDER July 21, 1931.

Filed June 13, 1929 2 Sheets-Sheet l .FIG-5' nu... ur

July 21, 1931. E. w. CARLSON LADDER I 2 Sheets-Sheet 2- Filed June 13. 1929 .FT-115MB'l SMM Patented July 21, 1931 narran srarss PATENT GFFECE ENOCTI W. CARLSON, F JAMES'I'OWN, NEW YORK, ASSIGNOR 0F ONE-HALF T0 BERTIL ANDERSON, OF JAMEVSTDWN, NEW YORK LADDER Application filed June 17-3, 1929.

This invention relates to an improvement in ladders and more particularly to a ladder .of the folding or collapsible type.

In its preferred embodiment this invention is directed to the provision of a ladder which, when not in use, is approximately one-tenth its extended length. The rails of the ladder are formed from` suitably pivoted members which members are extended or retracted by mechanical means easily operated by the user of the ladder.

It is Well known that prior to this invention ladders ofY this general 4type have been constructed, in fact, patents granted in the nineteenth century covered certain features of this type of ladder. It is believed, however, that no commercial success was ever attained with this type ladder for the reason that structurally they were incapable of supporting or holding up under the weight of work reoniired.` Applicant, by overcoming the structural disadvantages of ladders of this type, has perfected a device which will stand up under the same use thatany solid railed ladder will stand and at the same time materially decrease theweight thereof thereby facilitating easy transportation and erection. v

The principal object of this invention is therefore te provide a fol-ding extension ladder, the structure of which is of greaterV strength than a solid railv ladder of the same length.

An other object of this invention is the provision of a device of this class, the individual extendable rails of which have a four point suspension.

A further object of this invention is the provision lof adevice of .this class upon which is arranged a mechanical contrivance by which to extend and retain the ladder at any height desired.

Other and further objects of this invention will be apparent from a consideration of the following specification. when taken in `conjunction with the accompanying drawings; and in wh-iclr Fig. 1 is a fragmentary side elevation of one modification o f this invention in extended position; v ,y j

Serial No. 370,495.

Fig, 2 is a side elevation in collapsed posiien of the structure shown in Figure 1;

Fig. 3 is an enlarged vertical sectional view taken through one of the joints of the device, substantially on the line 3-3 of Figure 1;

Fig. il, is an enlarged fragmentary view taken substantially on the line 4:*4 of Figure 1 and showsthemethod of securing the rungs to the rails of the ladder;

Fig. 5V is a sectional view taken substantiallv7 on the line 5- 5 of Figure 1, and shows a part of the mechanical structure by which the ladder is operated;

Fig. 6 is a fragmentary front elevation; showing the ladder operating mechanism;

F ig. 7 is a fragmentary side elevation of the structure in Figure 1 and shows the ladder in partially extended position;

Fig. 8 is an enlarged detailed view of the operating structure; and

Fig. 9 is a slight modification of the structure shown in Figure 8.

Referring to the drawings this invention is generally indicated by the reference numeral 10 and comprises rails 12 and 13. Each rail is formed from a plurality of slats 141; pivotally joined together to facilitate extending or collapsing the ladder. Unlike ladders of this general type. the slats 1.11 are provided with four pivoted connections with .adjoining slats, one being located at ach end andv two at equal distances from the center.

VThe rails 12 and 13 are supported in spaced relation to .each other by means of rungs 15 and 16. Referring particularly to Figure 7 of the dra-wings, it will be noted that along one vertical face of the ladder, the rungs 15 are. mounted. being spaced apart a distance approximately half the spacing of the rangs 16 located on the. .other vert-ical face. Since the ladder is extendable; it is obvious that occasions will arise when it is desired to only partially extend it and at such times the rungs 1G are availed of for ascending, wher@ as, when the ladder is fully extended it is turned over and the rungs 15 are used. Comparison of Figures 1 and 7 clearly illustrates this double use, Figure 7 showing the `When the ladder is fully extended these rungs are too far apart and consequently must be reversed and the rungs 15 made use of.

The slats 14 are oined together by means of pivot members 17, having heads 18 and shanks 19. Openings 20 are formed in each of the slats 14 in which the shank 19 of the pivot member is mount-ed. Washers 21, one adjacent the head 18 and the other adjacent the end of the shank are supported on the pivot member. rihe end of the pivot member is headed over to form a shoulder 22 by which dislodgment thereof is prevented. Between adjacent slats, that are held together by the pivot member 17, rings or washers 23 are located. These Washers have an opening through which the shank 19 passes and are formed with circumferential teethlike edges 24 which engage the wood of each yslat. rl `he abutting face of the washers 23 are smooth and therefore reduce friction between abutting slats and-facilitate quick and easy operation of the ladder.

Attention is directed to the fact that the intermediate pivotal connections, by which the slats 14 are joined, are not fitted with rungs 15. The pivotal connections, however, at the ends of the slats have mounted thereon sockets 27. An opening 28, in the base of each socket, provides engagement with the head 18 of the pivotal member 17. Diametrically opposed openings 29 are formed in the walls of the socket. The rungs 15 yand 16 are transve 'sely drilled to provide openings 31 and w. ien the end of the rung is set into the socket 27 with the opening 31 therein aligned with the openings 29, a pin 33, having a head 34, is passed through the openings in said socket and said rung and flattened at its outer end to prevent dislodgment. By reason of the fact that the ends of each rung are encased, there is no tendency for them to split and break regardless of the abuse to which the ladder is subject-ed.

While it is contemplated that the ladder 10 will be made of a suliiciently light weight wood or other material to enable it be manually extended or collapsed, it is preferred to provide a mechanical manually operated device, by which to extend or retract said ladder. Referring to Figures G and 7, it will be noted that, in place of the intermediate pivot members 17, a mechanism 36 is mounted, being comprised of an arm 37 having teeth 38 formed along one edge thereof. A gear 40, having teeth 41, meshes with the teeth 38 of said arm. The pivoted end 39 of the arm is mounted upon one pair of abutting` slats and the gear 40 mounted upon the next adjacent pair. Rotation of the gear 40 will cause the end 39 to move toward or away from said gear and retract or extend the ladder. The bracket 42 is supported upon a shaft 43 which passes through the adjacent slats 14 and takes the place of the pivot members 17. The gear 40 is mounted upon the rod 43, being secured thereto in any suitable manner as by a set screw 44. The rod 43 is threaded adjacent its ends which lie beyond the edges of the slatted rails 12 and 13. One of these threaded ends is engaged by a handle 45 and the other end is fitted with a suitableV cap, (not shown). By reason of this structure, the handle 45 may be made to extend or retract the ladder from Whichever side is most convenient to the operator by merely interchanging it with the cap. It is to be understood there is an arm 37 and gear 40 for each rail of the ladder, that is, it is not contemplated to attempt to extend or retract the ladder by application of force on one side but to provide a mechanism which will operate to extend or retract both rails equally and simultaneously. Since the rod 43, by means of the handle 45, constitutes the power by which to rotate the gears 40, said gears will move the arms 37 and rails 12 an equal distanc In order to secure the ladder in any desired position and prevent collapsing thereof during use, a dog 45, pivotally supported upon the pin 46, is provided. The dog is adapted to engage the teeth 41 of the oea-r 40 and prevent rotation thereof in one direction. The pin 46, support-ing` the dog, is riveted or otherwise suitably secured to the bracket 42. It will be noted that the gear 40 and dog 45 are permanently mounted upon the bracket 42 and, consequently, when said bracket is mounted upon the ladder by means of the rod 43, it remains only necessary to insert the arm 37 in the channel 47 of said bracket and the device is ready for operation.

Referring now particularly to Figure 9 of the drawings, it is contemplated that, when a ladder having considerable extended length is used, the weight thereof will be too great to raise through the previously described mechanism. Additional gearing is therefore shown in this modification by which to reduce the speed with which the ladder is extended and comprises a small gear 4 mounted upon the shaft 43 and a large gear 50 secured upon the bracket 42. The gear 50 meshes with the teeth 38 of the arm 37 and a pivotally supported dog 52 controls the rotation of the gears. Through the use of the gears 49 and 50, it is contemplated that a ladder of this type, having an extended length up to fifty feet, may be successfully raised or lowered by one person.

,ln operation the ladder is placed flat on the ground, substantially as shown in `Figure 2 of the drawings, and the crank 45 is turned. rlurning the crank 45 rotates the shaft 43 and lgear 40. F The gear 40, being in engagement with the arm 37causes said arm to travel along said gear and extend the ladder. When the ladder has been extended to the desired length, the dog 45 is brought into engagement with the gear l0 and said ladder is ready for use.

Attention is directed to the fact that on occasion it would be desirous to extend the ladder only a portion of its possible length. Dilierently spaced rungs are therefore provided upon opposite faces of the ladder, the rungs l5 being for use when the ladder is fully extended, and the rungs 16 when the ladder is only partially extended.

Although applicant has shown and described but one modification of this invention and two modifications of the operating mechanism, he does not intend to be limited thereto since it is obvious that structural changes may be made without departing from the spirit and scope of this invention as set forth in the hereunto annexed claims.

Having thus set forth my invention what I claim as new and for which I desire protection by Letters Patent is:

l. An extendable ladder comprising a pair of rails, slats forming said rails, pivots connecting each of said slats with four adjacent slats, rungs mounted between and spacing said rails, means engaging and supporting the ends of said rungs on said rails and a manually operated gear and arm mechanism supported on connecting` slats of one of said rails, said means being adapted to extend or retract said ladder.

2. In an extendable ladder, a side rail, slats forming said rail, means pivotally connecting each of said slats, rungs located at the jointure of the ends of certain of said slats, and means engaging the end of each rung, said means being supported by certain of said pivotal means.

3. In an extendable ladder, a side rail formed from a'plurality of slats, pivots joining said slats together, said pivots connecting each of said slats with four adjacent slats, rungs mounted along` the front and rear faces of said ladder, said front rungs being twice in number that of said rear rungs.

4:. In an extendable ladder, a side rail formed from a plurality of slats, means pivotally joining each of said slats with four adjacent slats, rungs, sockets secured to certain of said pivotal means and supporting the ends of said rungs therein whereby to increase the strength of said rungs.

5. In an extendable ladder', a side rail formed from a plurality of slats, pivots joining said slats together, said pivots connecting each of said slats with four adjacent slats, rungs mounted along the front and rear faces of said ladder, the rungs along one face being substantially twice in number to those along the other face and sockets secured to certain of said pivots, said sockets supporting the ends of said rungs.

G. An extendable ladder comprising a pair of rails, slats forming said rails, pivots connecting each of said slats with adjacent slats, rungs mounted between and spacing said rails, sockets secured to certain of said pivots and supporting the ends of said rungs, and means mounted upon one of said rails, said means being adapted to extend or retract said ladder.

7. An extendable ladder comprising a pair of rails, pivotally connected slats forming said rails, sockets mounted upon said rails, rungs secured in said sockets, gears mounted upon said rails, an arm engaging one of said gears and a handle adapted to rotate said gear and move said arm whereby to extend or retract said ladder.

8. An extendable ladder comprising rails, slats forming said rails, pivots connecting each of said slats with four adjacent slats, sockets mounted upon said rails, rungs secured in said sockets, gears mounted on said rails and means on said rails engaged with and movable through the rotation of said gears whereby to extend or retract said ladder.

9. An extendable ladder comprising rails, slats forming said rails, pivots connecting each of said slats with four adjacent slats, sockets secured to said slats by means of said pivots, rungs having ends secured in said sockets, gears mounted on said rails and means pivotally joined to said slats engaging said gears whereby rotation of said gears moves said means to extend or retract said ladder.

10. In an extendable ladder comprising rails, slats forming said rails, pivots connecting each of said slats with four adjacent slats, sockets secured to certain of said slats by means of said pivots, rungs having ends secured in said sockets, said rungs being ar ranged in two sets, one of said sets being twice in number that of the other set, whereby to facilitate double use of said ladder.

ll. An extended ladder comprising rails, slats forming said rails, pivots connecting each of said slats with four adjacent slats, sockets secured to certain of said slats by means of said pivots, rungs having ends engaged by said sockets, gears mounted on said rails, arms operably engaging said gears, said rungs being arranged in two sets, one of said sets being twice in number that of the other set whereby when said ladder is extended through the rotation of said gears and movement of said arms either set of said rungs may be made use of.

In testimony whereof I have athxed my signature.

EN OCH W. CARLSON.

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